/*
** $Id: lstrlib.c,v 1.178 2012/08/14 18:12:34 roberto Exp $
** Standard library for string operations and pattern-matching
** See Copyright Notice in lua.h
*/


#include <ctype.h>
#include <stddef.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#define lstrlib_c
#define LUA_LIB

#include "lua.h"

#include "lauxlib.h"
#include "lualib.h"


/*
** maximum number of captures that a pattern can do during
** pattern-matching. This limit is arbitrary.
*/
#if !defined(LUA_MAXCAPTURES)
#define LUA_MAXCAPTURES 32
#endif


/* macro to `unsign' a character */
#define uchar(c) ((unsigned char)(c))



static int str_len(lua_State *L) {
    size_t l;
    luaL_checklstring(L, 1, &l);
    lua_pushinteger(L, (lua_Integer)l);
    return 1;
}


/* translate a relative string position: negative means back from end */
static size_t posrelat(ptrdiff_t pos, size_t len) {
    if (pos >= 0) return (size_t)pos;
    else if (0u - (size_t)pos > len) return 0;
    else return len - ((size_t) - pos) + 1;
}


static int str_sub(lua_State *L) {
    size_t l;
    const char *s = luaL_checklstring(L, 1, &l);
    size_t start = posrelat(luaL_checkinteger(L, 2), l);
    size_t end = posrelat(luaL_optinteger(L, 3, -1), l);
    if (start < 1) start = 1;
    if (end > l) end = l;
    if (start <= end)
        lua_pushlstring(L, s + start - 1, end - start + 1);
    else lua_pushliteral(L, "");
    return 1;
}


static int str_reverse(lua_State *L) {
    size_t l, i;
    luaL_Buffer b;
    const char *s = luaL_checklstring(L, 1, &l);
    char *p = luaL_buffinitsize(L, &b, l);
    for (i = 0; i < l; i++)
        p[i] = s[l - i - 1];
    luaL_pushresultsize(&b, l);
    return 1;
}


static int str_lower(lua_State *L) {
    size_t l;
    size_t i;
    luaL_Buffer b;
    const char *s = luaL_checklstring(L, 1, &l);
    char *p = luaL_buffinitsize(L, &b, l);
    for (i = 0; i < l; i++)
        p[i] = tolower(uchar(s[i]));
    luaL_pushresultsize(&b, l);
    return 1;
}


static int str_upper(lua_State *L) {
    size_t l;
    size_t i;
    luaL_Buffer b;
    const char *s = luaL_checklstring(L, 1, &l);
    char *p = luaL_buffinitsize(L, &b, l);
    for (i = 0; i < l; i++)
        p[i] = toupper(uchar(s[i]));
    luaL_pushresultsize(&b, l);
    return 1;
}


/* reasonable limit to avoid arithmetic overflow */
#define MAXSIZE ((~(size_t)0) >> 1)

static int str_rep(lua_State *L) {
    size_t l, lsep;
    const char *s = luaL_checklstring(L, 1, &l);
    int n = luaL_checkint(L, 2);
    const char *sep = luaL_optlstring(L, 3, "", &lsep);
    if (n <= 0) lua_pushliteral(L, "");
    else if (l + lsep < l || l + lsep >= MAXSIZE / n)  /* may overflow? */
        return luaL_error(L, "resulting string too large");
    else {
        size_t totallen = n * l + (n - 1) * lsep;
        luaL_Buffer b;
        char *p = luaL_buffinitsize(L, &b, totallen);
        while (n-- > 1) {  /* first n-1 copies (followed by separator) */
            memcpy(p, s, l * sizeof(char));
            p += l;
            if (lsep > 0) {  /* avoid empty 'memcpy' (may be expensive) */
                memcpy(p, sep, lsep * sizeof(char));
                p += lsep;
            }
        }
        memcpy(p, s, l * sizeof(char));  /* last copy (not followed by separator) */
        luaL_pushresultsize(&b, totallen);
    }
    return 1;
}


static int str_byte(lua_State *L) {
    size_t l;
    const char *s = luaL_checklstring(L, 1, &l);
    size_t posi = posrelat(luaL_optinteger(L, 2, 1), l);
    size_t pose = posrelat(luaL_optinteger(L, 3, posi), l);
    int n, i;
    if (posi < 1) posi = 1;
    if (pose > l) pose = l;
    if (posi > pose) return 0;  /* empty interval; return no values */
    n = (int)(pose -  posi + 1);
    if (posi + n <= pose)  /* (size_t -> int) overflow? */
        return luaL_error(L, "string slice too long");
    luaL_checkstack(L, n, "string slice too long");
    for (i = 0; i < n; i++)
        lua_pushinteger(L, uchar(s[posi + i - 1]));
    return n;
}


static int str_char(lua_State *L) {
    int n = lua_gettop(L);  /* number of arguments */
    int i;
    luaL_Buffer b;
    char *p = luaL_buffinitsize(L, &b, n);
    for (i = 1; i <= n; i++) {
        int c = luaL_checkint(L, i);
        luaL_argcheck(L, uchar(c) == c, i, "value out of range");
        p[i - 1] = uchar(c);
    }
    luaL_pushresultsize(&b, n);
    return 1;
}


static int writer(lua_State *L, const void *b, size_t size, void *B) {
    (void)L;
    luaL_addlstring((luaL_Buffer *) B, (const char *)b, size);
    return 0;
}


static int str_dump(lua_State *L) {
    luaL_Buffer b;
    luaL_checktype(L, 1, LUA_TFUNCTION);
    lua_settop(L, 1);
    luaL_buffinit(L, &b);
    if (lua_dump(L, writer, &b) != 0)
        return luaL_error(L, "unable to dump given function");
    luaL_pushresult(&b);
    return 1;
}



/*
** {======================================================
** PATTERN MATCHING
** =======================================================
*/


#define CAP_UNFINISHED (-1)
#define CAP_POSITION   (-2)


typedef struct MatchState {
    int matchdepth;  /* control for recursive depth (to avoid C stack overflow) */
    const char *src_init;  /* init of source string */
    const char *src_end;  /* end ('\0') of source string */
    const char *p_end;  /* end ('\0') of pattern */
    lua_State *L;
    int level;  /* total number of captures (finished or unfinished) */
    struct {
        const char *init;
        ptrdiff_t len;
    } capture[LUA_MAXCAPTURES];
} MatchState;


/* recursive function */
static const char *match(MatchState *ms, const char *s, const char *p);


/* maximum recursion depth for 'match' */
#if !defined(MAXCCALLS)
#define MAXCCALLS 200
#endif


#define L_ESC '%'
#define SPECIALS "^$*+?.([%-"


static int check_capture(MatchState *ms, int l) {
    l -= '1';
    if (l < 0 || l >= ms->level || ms->capture[l].len == CAP_UNFINISHED)
        return luaL_error(ms->L, "invalid capture index %%%d", l + 1);
    return l;
}


static int capture_to_close(MatchState *ms) {
    int level = ms->level;
    for (level--; level >= 0; level--)
        if (ms->capture[level].len == CAP_UNFINISHED) return level;
    return luaL_error(ms->L, "invalid pattern capture");
}


static const char *classend(MatchState *ms, const char *p) {
    switch (*p++) {
        case L_ESC: {
            if (p == ms->p_end)
                luaL_error(ms->L, "malformed pattern (ends with " LUA_QL("%%") ")");
            return p + 1;
        }
        case '[': {
            if (*p == '^') p++;
            do {  /* look for a `]' */
                if (p == ms->p_end)
                    luaL_error(ms->L, "malformed pattern (missing " LUA_QL("]") ")");
                if (*(p++) == L_ESC && p < ms->p_end)
                    p++;  /* skip escapes (e.g. `%]') */
            } while (*p != ']');
            return p + 1;
        }
        default: {
            return p;
        }
    }
}


static int match_class(int c, int cl) {
    int res;
    switch (tolower(cl)) {
        case 'a' :
            res = isalpha(c);
            break;
        case 'c' :
            res = iscntrl(c);
            break;
        case 'd' :
            res = isdigit(c);
            break;
        case 'g' :
            res = isgraph(c);
            break;
        case 'l' :
            res = islower(c);
            break;
        case 'p' :
            res = ispunct(c);
            break;
        case 's' :
            res = isspace(c);
            break;
        case 'u' :
            res = isupper(c);
            break;
        case 'w' :
            res = isalnum(c);
            break;
        case 'x' :
            res = isxdigit(c);
            break;
        case 'z' :
            res = (c == 0);
            break;  /* deprecated option */
        default:
            return (cl == c);
    }
    return (islower(cl) ? res : !res);
}


static int matchbracketclass(int c, const char *p, const char *ec) {
    int sig = 1;
    if (*(p + 1) == '^') {
        sig = 0;
        p++;  /* skip the `^' */
    }
    while (++p < ec) {
        if (*p == L_ESC) {
            p++;
            if (match_class(c, uchar(*p)))
                return sig;
        } else if ((*(p + 1) == '-') && (p + 2 < ec)) {
            p += 2;
            if (uchar(*(p - 2)) <= c && c <= uchar(*p))
                return sig;
        } else if (uchar(*p) == c) return sig;
    }
    return !sig;
}


static int singlematch(MatchState *ms, const char *s, const char *p,
                       const char *ep) {
    if (s >= ms->src_end)
        return 0;
    else {
        int c = uchar(*s);
        switch (*p) {
            case '.':
                return 1;  /* matches any char */
            case L_ESC:
                return match_class(c, uchar(*(p + 1)));
            case '[':
                return matchbracketclass(c, p, ep - 1);
            default:
                return (uchar(*p) == c);
        }
    }
}


static const char *matchbalance(MatchState *ms, const char *s,
                                const char *p) {
    if (p >= ms->p_end - 1)
        luaL_error(ms->L, "malformed pattern "
                   "(missing arguments to " LUA_QL("%%b") ")");
    if (*s != *p) return NULL;
    else {
        int b = *p;
        int e = *(p + 1);
        int cont = 1;
        while (++s < ms->src_end) {
            if (*s == e) {
                if (--cont == 0) return s + 1;
            } else if (*s == b) cont++;
        }
    }
    return NULL;  /* string ends out of balance */
}


static const char *max_expand(MatchState *ms, const char *s,
                              const char *p, const char *ep) {
    ptrdiff_t i = 0;  /* counts maximum expand for item */
    while (singlematch(ms, s + i, p, ep))
        i++;
    /* keeps trying to match with the maximum repetitions */
    while (i >= 0) {
        const char *res = match(ms, (s + i), ep + 1);
        if (res) return res;
        i--;  /* else didn't match; reduce 1 repetition to try again */
    }
    return NULL;
}


static const char *min_expand(MatchState *ms, const char *s,
                              const char *p, const char *ep) {
    for (;;) {
        const char *res = match(ms, s, ep + 1);
        if (res != NULL)
            return res;
        else if (singlematch(ms, s, p, ep))
            s++;  /* try with one more repetition */
        else return NULL;
    }
}


static const char *start_capture(MatchState *ms, const char *s,
                                 const char *p, int what) {
    const char *res;
    int level = ms->level;
    if (level >= LUA_MAXCAPTURES) luaL_error(ms->L, "too many captures");
    ms->capture[level].init = s;
    ms->capture[level].len = what;
    ms->level = level + 1;
    if ((res = match(ms, s, p)) == NULL) /* match failed? */
        ms->level--;  /* undo capture */
    return res;
}


static const char *end_capture(MatchState *ms, const char *s,
                               const char *p) {
    int l = capture_to_close(ms);
    const char *res;
    ms->capture[l].len = s - ms->capture[l].init;  /* close capture */
    if ((res = match(ms, s, p)) == NULL)  /* match failed? */
        ms->capture[l].len = CAP_UNFINISHED;  /* undo capture */
    return res;
}


static const char *match_capture(MatchState *ms, const char *s, int l) {
    size_t len;
    l = check_capture(ms, l);
    len = ms->capture[l].len;
    if ((size_t)(ms->src_end - s) >= len &&
            memcmp(ms->capture[l].init, s, len) == 0)
        return s + len;
    else return NULL;
}


static const char *match(MatchState *ms, const char *s, const char *p) {
    if (ms->matchdepth-- == 0)
        luaL_error(ms->L, "pattern too complex");
init: /* using goto's to optimize tail recursion */
    if (p != ms->p_end) {  /* end of pattern? */
        switch (*p) {
            case '(': {  /* start capture */
                if (*(p + 1) == ')')  /* position capture? */
                    s = start_capture(ms, s, p + 2, CAP_POSITION);
                else
                    s = start_capture(ms, s, p + 1, CAP_UNFINISHED);
                break;
            }
            case ')': {  /* end capture */
                s = end_capture(ms, s, p + 1);
                break;
            }
            case '$': {
                if ((p + 1) != ms->p_end)  /* is the `$' the last char in pattern? */
                    goto dflt;  /* no; go to default */
                s = (s == ms->src_end) ? s : NULL;  /* check end of string */
                break;
            }
            case L_ESC: {  /* escaped sequences not in the format class[*+?-]? */
                switch (*(p + 1)) {
                    case 'b': {  /* balanced string? */
                        s = matchbalance(ms, s, p + 2);
                        if (s != NULL) {
                            p += 4;
                            goto init;  /* return match(ms, s, p + 4); */
                        }  /* else fail (s == NULL) */
                        break;
                    }
                    case 'f': {  /* frontier? */
                        const char *ep;
                        char previous;
                        p += 2;
                        if (*p != '[')
                            luaL_error(ms->L, "missing " LUA_QL("[") " after "
                                       LUA_QL("%%f") " in pattern");
                        ep = classend(ms, p);  /* points to what is next */
                        previous = (s == ms->src_init) ? '\0' : *(s - 1);
                        if (!matchbracketclass(uchar(previous), p, ep - 1) &&
                                matchbracketclass(uchar(*s), p, ep - 1)) {
                            p = ep;
                            goto init;  /* return match(ms, s, ep); */
                        }
                        s = NULL;  /* match failed */
                        break;
                    }
                    case '0':
                    case '1':
                    case '2':
                    case '3':
                    case '4':
                    case '5':
                    case '6':
                    case '7':
                    case '8':
                    case '9': {  /* capture results (%0-%9)? */
                        s = match_capture(ms, s, uchar(*(p + 1)));
                        if (s != NULL) {
                            p += 2;
                            goto init;  /* return match(ms, s, p + 2) */
                        }
                        break;
                    }
                    default:
                        goto dflt;
                }
                break;
            }
            default:
dflt: {  /* pattern class plus optional suffix */
                    const char *ep = classend(ms, p);  /* points to optional suffix */
                    /* does not match at least once? */
                    if (!singlematch(ms, s, p, ep)) {
                        if (*ep == '*' || *ep == '?' || *ep == '-') {  /* accept empty? */
                            p = ep + 1;
                            goto init;  /* return match(ms, s, ep + 1); */
                        } else /* '+' or no suffix */
                            s = NULL;  /* fail */
                    } else { /* matched once */
                        switch (*ep) {  /* handle optional suffix */
                            case '?': {  /* optional */
                                const char *res;
                                if ((res = match(ms, s + 1, ep + 1)) != NULL)
                                    s = res;
                                else {
                                    p = ep + 1;
                                    goto init;  /* else return match(ms, s, ep + 1); */
                                }
                                break;
                            }
                            case '+':  /* 1 or more repetitions */
                                s++;  /* 1 match already done */
                            /* go through */
                            case '*':  /* 0 or more repetitions */
                                s = max_expand(ms, s, p, ep);
                                break;
                            case '-':  /* 0 or more repetitions (minimum) */
                                s = min_expand(ms, s, p, ep);
                                break;
                            default:  /* no suffix */
                                s++;
                                p = ep;
                                goto init;  /* return match(ms, s + 1, ep); */
                        }
                    }
                    break;
                }
        }
    }
    ms->matchdepth++;
    return s;
}



static const char *lmemfind(const char *s1, size_t l1,
                            const char *s2, size_t l2) {
    if (l2 == 0) return s1;  /* empty strings are everywhere */
    else if (l2 > l1) return NULL;  /* avoids a negative `l1' */
    else {
        const char *init;  /* to search for a `*s2' inside `s1' */
        l2--;  /* 1st char will be checked by `memchr' */
        l1 = l1 - l2; /* `s2' cannot be found after that */
        while (l1 > 0 && (init = (const char *)memchr(s1, *s2, l1)) != NULL) {
            init++;   /* 1st char is already checked */
            if (memcmp(init, s2 + 1, l2) == 0)
                return init - 1;
            else {  /* correct `l1' and `s1' to try again */
                l1 -= init - s1;
                s1 = init;
            }
        }
        return NULL;  /* not found */
    }
}


static void push_onecapture(MatchState *ms, int i, const char *s,
                            const char *e) {
    if (i >= ms->level) {
        if (i == 0)  /* ms->level == 0, too */
            lua_pushlstring(ms->L, s, e - s);  /* add whole match */
        else
            luaL_error(ms->L, "invalid capture index");
    } else {
        ptrdiff_t l = ms->capture[i].len;
        if (l == CAP_UNFINISHED) luaL_error(ms->L, "unfinished capture");
        if (l == CAP_POSITION)
            lua_pushinteger(ms->L, ms->capture[i].init - ms->src_init + 1);
        else
            lua_pushlstring(ms->L, ms->capture[i].init, l);
    }
}


static int push_captures(MatchState *ms, const char *s, const char *e) {
    int i;
    int nlevels = (ms->level == 0 && s) ? 1 : ms->level;
    luaL_checkstack(ms->L, nlevels, "too many captures");
    for (i = 0; i < nlevels; i++)
        push_onecapture(ms, i, s, e);
    return nlevels;  /* number of strings pushed */
}


/* check whether pattern has no special characters */
static int nospecials(const char *p, size_t l) {
    size_t upto = 0;
    do {
        if (strpbrk(p + upto, SPECIALS))
            return 0;  /* pattern has a special character */
        upto += strlen(p + upto) + 1;  /* may have more after \0 */
    } while (upto <= l);
    return 1;  /* no special chars found */
}


static int str_find_aux(lua_State *L, int find) {
    size_t ls, lp;
    const char *s = luaL_checklstring(L, 1, &ls);
    const char *p = luaL_checklstring(L, 2, &lp);
    size_t init = posrelat(luaL_optinteger(L, 3, 1), ls);
    if (init < 1) init = 1;
    else if (init > ls + 1) {  /* start after string's end? */
        lua_pushnil(L);  /* cannot find anything */
        return 1;
    }
    /* explicit request or no special characters? */
    if (find && (lua_toboolean(L, 4) || nospecials(p, lp))) {
        /* do a plain search */
        const char *s2 = lmemfind(s + init - 1, ls - init + 1, p, lp);
        if (s2) {
            lua_pushinteger(L, s2 - s + 1);
            lua_pushinteger(L, s2 - s + lp);
            return 2;
        }
    } else {
        MatchState ms;
        const char *s1 = s + init - 1;
        int anchor = (*p == '^');
        if (anchor) {
            p++;
            lp--;  /* skip anchor character */
        }
        ms.L = L;
        ms.matchdepth = MAXCCALLS;
        ms.src_init = s;
        ms.src_end = s + ls;
        ms.p_end = p + lp;
        do {
            const char *res;
            ms.level = 0;
            lua_assert(ms.matchdepth == MAXCCALLS);
            if ((res = match(&ms, s1, p)) != NULL) {
                if (find) {
                    lua_pushinteger(L, s1 - s + 1);  /* start */
                    lua_pushinteger(L, res - s);   /* end */
                    return push_captures(&ms, NULL, 0) + 2;
                } else
                    return push_captures(&ms, s1, res);
            }
        } while (s1++ < ms.src_end && !anchor);
    }
    lua_pushnil(L);  /* not found */
    return 1;
}


static int str_find(lua_State *L) {
    return str_find_aux(L, 1);
}


static int str_match(lua_State *L) {
    return str_find_aux(L, 0);
}


static int gmatch_aux(lua_State *L) {
    MatchState ms;
    size_t ls, lp;
    const char *s = lua_tolstring(L, lua_upvalueindex(1), &ls);
    const char *p = lua_tolstring(L, lua_upvalueindex(2), &lp);
    const char *src;
    ms.L = L;
    ms.matchdepth = MAXCCALLS;
    ms.src_init = s;
    ms.src_end = s + ls;
    ms.p_end = p + lp;
    for (src = s + (size_t)lua_tointeger(L, lua_upvalueindex(3));
            src <= ms.src_end;
            src++) {
        const char *e;
        ms.level = 0;
        lua_assert(ms.matchdepth == MAXCCALLS);
        if ((e = match(&ms, src, p)) != NULL) {
            lua_Integer newstart = e - s;
            if (e == src) newstart++;  /* empty match? go at least one position */
            lua_pushinteger(L, newstart);
            lua_replace(L, lua_upvalueindex(3));
            return push_captures(&ms, src, e);
        }
    }
    return 0;  /* not found */
}


static int gmatch(lua_State *L) {
    luaL_checkstring(L, 1);
    luaL_checkstring(L, 2);
    lua_settop(L, 2);
    lua_pushinteger(L, 0);
    lua_pushcclosure(L, gmatch_aux, 3);
    return 1;
}


static void add_s(MatchState *ms, luaL_Buffer *b, const char *s,
                  const char *e) {
    size_t l, i;
    const char *news = lua_tolstring(ms->L, 3, &l);
    for (i = 0; i < l; i++) {
        if (news[i] != L_ESC)
            luaL_addchar(b, news[i]);
        else {
            i++;  /* skip ESC */
            if (!isdigit(uchar(news[i]))) {
                if (news[i] != L_ESC)
                    luaL_error(ms->L, "invalid use of " LUA_QL("%c")
                               " in replacement string", L_ESC);
                luaL_addchar(b, news[i]);
            } else if (news[i] == '0')
                luaL_addlstring(b, s, e - s);
            else {
                push_onecapture(ms, news[i] - '1', s, e);
                luaL_addvalue(b);  /* add capture to accumulated result */
            }
        }
    }
}


static void add_value(MatchState *ms, luaL_Buffer *b, const char *s,
                      const char *e, int tr) {
    lua_State *L = ms->L;
    switch (tr) {
        case LUA_TFUNCTION: {
            int n;
            lua_pushvalue(L, 3);
            n = push_captures(ms, s, e);
            lua_call(L, n, 1);
            break;
        }
        case LUA_TTABLE: {
            push_onecapture(ms, 0, s, e);
            lua_gettable(L, 3);
            break;
        }
        default: {  /* LUA_TNUMBER or LUA_TSTRING */
            add_s(ms, b, s, e);
            return;
        }
    }
    if (!lua_toboolean(L, -1)) {  /* nil or false? */
        lua_pop(L, 1);
        lua_pushlstring(L, s, e - s);  /* keep original text */
    } else if (!lua_isstring(L, -1))
        luaL_error(L, "invalid replacement value (a %s)", luaL_typename(L, -1));
    luaL_addvalue(b);  /* add result to accumulator */
}


static int str_gsub(lua_State *L) {
    size_t srcl, lp;
    const char *src = luaL_checklstring(L, 1, &srcl);
    const char *p = luaL_checklstring(L, 2, &lp);
    int tr = lua_type(L, 3);
    size_t max_s = luaL_optinteger(L, 4, srcl + 1);
    int anchor = (*p == '^');
    size_t n = 0;
    MatchState ms;
    luaL_Buffer b;
    luaL_argcheck(L, tr == LUA_TNUMBER || tr == LUA_TSTRING ||
                  tr == LUA_TFUNCTION || tr == LUA_TTABLE, 3,
                  "string/function/table expected");
    luaL_buffinit(L, &b);
    if (anchor) {
        p++;
        lp--;  /* skip anchor character */
    }
    ms.L = L;
    ms.matchdepth = MAXCCALLS;
    ms.src_init = src;
    ms.src_end = src + srcl;
    ms.p_end = p + lp;
    while (n < max_s) {
        const char *e;
        ms.level = 0;
        lua_assert(ms.matchdepth == MAXCCALLS);
        e = match(&ms, src, p);
        if (e) {
            n++;
            add_value(&ms, &b, src, e, tr);
        }
        if (e && e > src) /* non empty match? */
            src = e;  /* skip it */
        else if (src < ms.src_end)
            luaL_addchar(&b, *src++);
        else break;
        if (anchor) break;
    }
    luaL_addlstring(&b, src, ms.src_end - src);
    luaL_pushresult(&b);
    lua_pushinteger(L, n);  /* number of substitutions */
    return 2;
}

/* }====================================================== */



/*
** {======================================================
** STRING FORMAT
** =======================================================
*/

/*
** LUA_INTFRMLEN is the length modifier for integer conversions in
** 'string.format'; LUA_INTFRM_T is the integer type corresponding to
** the previous length
*/
#if !defined(LUA_INTFRMLEN) /* { */
#if defined(LUA_USE_LONGLONG)

#define LUA_INTFRMLEN "ll"
#define LUA_INTFRM_T long long

#else

#define LUA_INTFRMLEN "l"
#define LUA_INTFRM_T long

#endif
#endif                      /* } */


/*
** LUA_FLTFRMLEN is the length modifier for float conversions in
** 'string.format'; LUA_FLTFRM_T is the float type corresponding to
** the previous length
*/
#if !defined(LUA_FLTFRMLEN)

#define LUA_FLTFRMLEN ""
#define LUA_FLTFRM_T double

#endif


/* maximum size of each formatted item (> len(format('%99.99f', -1e308))) */
#define MAX_ITEM 512
/* valid flags in a format specification */
#define FLAGS "-+ #0"
/*
** maximum size of each format specification (such as '%-099.99d')
** (+10 accounts for %99.99x plus margin of error)
*/
#define MAX_FORMAT (sizeof(FLAGS) + sizeof(LUA_INTFRMLEN) + 10)


static void addquoted(lua_State *L, luaL_Buffer *b, int arg) {
    size_t l;
    const char *s = luaL_checklstring(L, arg, &l);
    luaL_addchar(b, '"');
    while (l--) {
        if (*s == '"' || *s == '\\' || *s == '\n') {
            luaL_addchar(b, '\\');
            luaL_addchar(b, *s);
        } else if (*s == '\0' || iscntrl(uchar(*s))) {
            char buff[10];
            if (!isdigit(uchar(*(s + 1))))
                sprintf(buff, "\\%d", (int)uchar(*s));
            else
                sprintf(buff, "\\%03d", (int)uchar(*s));
            luaL_addstring(b, buff);
        } else
            luaL_addchar(b, *s);
        s++;
    }
    luaL_addchar(b, '"');
}

static const char *scanformat(lua_State *L, const char *strfrmt, char *form) {
    const char *p = strfrmt;
    while (*p != '\0' && strchr(FLAGS, *p) != NULL) p++;  /* skip flags */
    if ((size_t)(p - strfrmt) >= sizeof(FLAGS) / sizeof(char))
        luaL_error(L, "invalid format (repeated flags)");
    if (isdigit(uchar(*p))) p++;  /* skip width */
    if (isdigit(uchar(*p))) p++;  /* (2 digits at most) */
    if (*p == '.') {
        p++;
        if (isdigit(uchar(*p))) p++;  /* skip precision */
        if (isdigit(uchar(*p))) p++;  /* (2 digits at most) */
    }
    if (isdigit(uchar(*p)))
        luaL_error(L, "invalid format (width or precision too long)");
    *(form++) = '%';
    memcpy(form, strfrmt, (p - strfrmt + 1) * sizeof(char));
    form += p - strfrmt + 1;
    *form = '\0';
    return p;
}


/*
** add length modifier into formats
*/
static void addlenmod(char *form, const char *lenmod) {
    size_t l = strlen(form);
    size_t lm = strlen(lenmod);
    char spec = form[l - 1];
    strcpy(form + l - 1, lenmod);
    form[l + lm - 1] = spec;
    form[l + lm] = '\0';
}


static int str_format(lua_State *L) {
    int top = lua_gettop(L);
    int arg = 1;
    size_t sfl;
    const char *strfrmt = luaL_checklstring(L, arg, &sfl);
    const char *strfrmt_end = strfrmt + sfl;
    luaL_Buffer b;
    luaL_buffinit(L, &b);
    while (strfrmt < strfrmt_end) {
        if (*strfrmt != L_ESC)
            luaL_addchar(&b, *strfrmt++);
        else if (*++strfrmt == L_ESC)
            luaL_addchar(&b, *strfrmt++);  /* %% */
        else { /* format item */
            char form[MAX_FORMAT];  /* to store the format (`%...') */
            char *buff = luaL_prepbuffsize(&b, MAX_ITEM);  /* to put formatted item */
            int nb = 0;  /* number of bytes in added item */
            if (++arg > top)
                luaL_argerror(L, arg, "no value");
            strfrmt = scanformat(L, strfrmt, form);
            switch (*strfrmt++) {
                case 'c': {
                    nb = sprintf(buff, form, luaL_checkint(L, arg));
                    break;
                }
                case 'd':
                case 'i': {
                    lua_Number n = luaL_checknumber(L, arg);
                    LUA_INTFRM_T ni = (LUA_INTFRM_T)n;
                    lua_Number diff = n - (lua_Number)ni;
                    luaL_argcheck(L, -1 < diff && diff < 1, arg,
                                  "not a number in proper range");
                    addlenmod(form, LUA_INTFRMLEN);
                    nb = sprintf(buff, form, ni);
                    break;
                }
                case 'o':
                case 'u':
                case 'x':
                case 'X': {
                    lua_Number n = luaL_checknumber(L, arg);
                    unsigned LUA_INTFRM_T ni = (unsigned LUA_INTFRM_T)n;
                    lua_Number diff = n - (lua_Number)ni;
                    luaL_argcheck(L, -1 < diff && diff < 1, arg,
                                  "not a non-negative number in proper range");
                    addlenmod(form, LUA_INTFRMLEN);
                    nb = sprintf(buff, form, ni);
                    break;
                }
                case 'e':
                case 'E':
                case 'f':
#if defined(LUA_USE_AFORMAT)
                case 'a':
                case 'A':
#endif
                case 'g':
                case 'G': {
                    addlenmod(form, LUA_FLTFRMLEN);
                    nb = sprintf(buff, form, (LUA_FLTFRM_T)luaL_checknumber(L, arg));
                    break;
                }
                case 'q': {
                    addquoted(L, &b, arg);
                    break;
                }
                case 's': {
                    size_t l;
                    const char *s = luaL_tolstring(L, arg, &l);
                    if (!strchr(form, '.') && l >= 100) {
                        /* no precision and string is too long to be formatted;
                           keep original string */
                        luaL_addvalue(&b);
                        break;
                    } else {
                        nb = sprintf(buff, form, s);
                        lua_pop(L, 1);  /* remove result from 'luaL_tolstring' */
                        break;
                    }
                }
                default: {  /* also treat cases `pnLlh' */
                    return luaL_error(L, "invalid option " LUA_QL("%%%c") " to "
                                      LUA_QL("format"), *(strfrmt - 1));
                }
            }
            luaL_addsize(&b, nb);
        }
    }
    luaL_pushresult(&b);
    return 1;
}

/* }====================================================== */


static const luaL_Reg strlib[] = {
    {"byte", str_byte},
    {"char", str_char},
    {"dump", str_dump},
    {"find", str_find},
    {"format", str_format},
    {"gmatch", gmatch},
    {"gsub", str_gsub},
    {"len", str_len},
    {"lower", str_lower},
    {"match", str_match},
    {"rep", str_rep},
    {"reverse", str_reverse},
    {"sub", str_sub},
    {"upper", str_upper},
    {NULL, NULL}
};


static void createmetatable(lua_State *L) {
    lua_createtable(L, 0, 1);  /* table to be metatable for strings */
    lua_pushliteral(L, "");  /* dummy string */
    lua_pushvalue(L, -2);  /* copy table */
    lua_setmetatable(L, -2);  /* set table as metatable for strings */
    lua_pop(L, 1);  /* pop dummy string */
    lua_pushvalue(L, -2);  /* get string library */
    lua_setfield(L, -2, "__index");  /* metatable.__index = string */
    lua_pop(L, 1);  /* pop metatable */
}


/*
** Open string library
*/
LUAMOD_API int luaopen_string(lua_State *L) {
    luaL_newlib(L, strlib);
    createmetatable(L);
    return 1;
}

